You can tell that this is an image of a DNA nucleotide and not an RNA nucleotide because you see a _____.

Here is the answer to You can tell that this is an image of a DNA nucleotide and not an RNA nucleotide because you see a _____.

It belonged to the MCAT practice test (Human Anatomy & Physiology basic part ).

You can tell that this is an image of a DNA nucleotide and not an RNA nucleotide because you see a _____.

Nucleotides

Nucleotides are a class of compounds consisting of three substances: purine bases or pyrimidine bases, ribose or deoxyribose, and phosphoric acid, also known as nucleosides.

Pentose and organic bases synthesize nucleotides, nucleosides, and phosphate synthesize nucleotides, and four nucleotides make up nucleic acids. Nucleotides are mainly involved in the composition of nucleic acids, and many single nucleotides also have a variety of important biological functions, such as adenosine triphosphate (ATP) and dehydrocoenzyme, which are related to energy metabolism.

A class of compounds consisting of three substances: purine bases or pyrimidine bases, ribose or deoxyribose, and phosphate, also known as nucleosides.

Pentasaccharides and organic bases synthesize nucleotides, nucleosides, and phosphate synthesize nucleotides, and four nucleotides make up nucleic acids. Nucleotides are mainly involved in the composition of nucleic acids, and many single nucleotides also have a variety of important biological functions, such as adenosine triphosphate (ATP) and dehydrocoenzyme, which are related to energy metabolism.

Some analogs of nucleotides can interfere with nucleotide metabolism and can be used as anticancer drugs. According to sugar, there are two types of nucleotides: ribonucleotides and deoxyribonucleotides.

Depending on the base, there are adenine nucleotides (AMP), guanine nucleotides (GMP), cytosine nucleotides (CMP), uracil nucleotides (UMP), thymine nucleotides (TMP), and hypoxanthine nucleotides (IMP).

The phosphate in nucleotides is available in one-, two- and three-molecule forms. In addition, nucleotide molecules can be dehydrated and condensed to form cyclic nucleotides.

In 1919, a Russian-American physician and chemist, Phoebus Levine, first discovered the order of the three main components of mononucleotides (phosphate, pentose, and nitrogen groups). He was also the first to discover the carbohydrate components of ribonucleic acid (ribose) and deoxyribonucleic acid (deoxyribose).

Nucleotides are the basic building blocks of ribonucleic acid and deoxyribonucleic acid, which are the precursors of synthetic nucleic acids in the body. Nucleotides are distributed in the nucleus and cytoplasm of organs, tissues, and cells in living organisms along with nucleic acids, and participate in basic life activities such as genetics, development, and growth as constituents of nucleic acids.

There are also considerable amounts of nucleotides in free form in living organisms. Adenosine triphosphate plays a major role in cellular energy metabolism. The release and absorption of energy in the body are mainly reflected by the production and consumption of adenosine triphosphate.

In addition, uridine triphosphate, cytidine triphosphate, and guanosine triphosphate are also sources of energy in the anabolism of some substances. Adenosine is also a component of some coenzymes, such as coenzyme I, coenzyme II and coenzyme A.

In living organisms, nucleotides can be synthesized from a number of simple compounds. These synthesis materials include aspartic acid, glycine, glutamine, one-carbon units, and CO2. Purine nucleotides are catabolized in the body to produce uric acid, and pyrimidine nucleotides are catabolized to produce CO2, β-alanine, and β-aminoisobutyric acid. Disorders in the metabolism of purine and pyrimidine nucleotides can cause clinical symptoms.

Nucleotide compounds are also used as drugs in clinical treatment, such as 5-fluorouracil and 6-mercaptopurine, which are commonly used in oncology chemotherapy.

Some nucleotide molecules have only one phosphate group, so they are called nucleoside monophosphate (NMP). 5′-Nucleotide phosphate groups can be further phosphorylated to form nucleoside diphosphate (NDP) and nucleoside triphosphate (NTP), in which the phosphates are linked by high-energy bonds. The same is true for deoxyribonucleotides.

There is also a class of cyclized nucleotides in vivo, in which the phosphate portion of a single nucleotide is simultaneously dehydrated and condensed with the third and fifth carbon atoms of the ribose to form a cyclic diester, i.e., 3′,5′-cyclized nucleotides, the important ones being 3′,5′-cyclic adenosine monophosphate (cAMP) and 3′,5′-cyclic guanosine monophosphate (cGMP).

Nucleotides are the basic structural units of nucleic acids, which are mainly synthesized by the body’s cells themselves. Nucleotides are widely distributed in the body.

They are mainly present in cells in the form of 5′-nucleotides. The concentration of ribonucleotides in cells far exceeds that of deoxyribonucleotides. The content of various nucleotides in different types of cells varies greatly. In the same cell, the content of various nucleotides also varies, and the total amount of nucleotides does not vary much.

Function

Nucleotides have important biological functions and are involved in almost all biochemical processes in living organisms. They are summarized in the following five aspects.

1) Nucleotides are the precursors for the synthesis of biological macromolecules ribonucleic acid (RNA) and deoxyribonucleic acid (DNA). there are four main types of nucleotides in RNA: AMP, GMP, CMP, and UMP, which are synthesized from scratch from simple substances such as ribose phosphate, amino acids, one-carbon units, and carbon dioxide. there are four main types of deoxyribonucleotides in DNA. dAMP, dGMP, dCMP, and dTMP, which are made by reduction of their respective corresponding nuclear carbon nucleotides at the diphosphate level.

2) Adenosine triphosphate (ATP) plays an extremely important role in cellular energy metabolism. The energy produced during the oxidation of substances is partly stored in the high-energy phosphate bonds of the ATP molecule, which can be used in conjunction with various biological reactions that require energy to perform various physiological functions, such as the anabolism of substances, muscle contraction, absorption and secretion, body temperature maintenance, and bioelectric activity. Therefore, ATP can be considered the center of energy metabolic transformation.

3) ATP can also transfer high-energy phosphate bonds to UDP, CDP, and GDP to produce UTP, CTP, and GTP, which are also direct sources of energy in some anabolic reactions. Moreover, some nucleotide derivatives are also activated intermediate metabolites in some synthetic reactions. For example, UTP is involved in glycogen synthesis for energy supply, and UDP also has a role in carrying glucose for transport.

4) Adenosine is also a component of several important coenzymes, such as coenzyme I (nicotinamide adenine dinucleotide, NAD+), coenzyme II (nicotinamide adenine dinucleotide phosphate, NADP+), flavin adenine dinucleotide (FAD), and coenzyme A (CoA), which are important components of biological oxidation systems and play an important role in the transfer of hydrogen atoms or electrons. CoA is a coenzyme component of some enzymes and is involved in the aerobic oxidation of sugars and fatty acid oxidation.

5) Nucleotides have a regulatory role in many basic biological processes. The basic components of all living organisms play a dominant role in the growth, development, reproduction, and genetics of organisms. For example, milk powder has a role in maintaining the normal function of the baby’s gastrointestinal tract, reducing diarrhea and constipation, improving immunity, and less illness.

Ribonucleic acid (RNA)

Ribonucleic acid (abbreviated as RNA, or Ribonucleic Acid) is a carrier of genetic information found in living cells and in some viruses and virus-like organisms, RNA consists of ribonucleotides condensed by phosphodiester bonds to form long chain-like molecules. A ribonucleic acid molecule is composed of phosphate, ribose, and bases.

There are four main bases in RNA, namely A (adenine), G (guanine), C (cytosine), and U (uracil), where U (uracil) replaces T in DNA. ribonucleic acid’s role in the body is mainly to guide protein synthesis.

One cell in the human body contains about 10 pg of RNA (containing about 7 pg of DNA). Compared to DNA, RNA is diverse, has a smaller molecular weight, and is highly variable in content.

RNA can be divided into messenger RNA and non-coding RNA according to structure and function. non-coding RNA is divided into non-coding large RNA and non-coding small RNA. non-coding large RNA includes ribosomal RNA, long-chain non-coding RNA. non-coding small RNA includes transfer RNA, nuclease, small molecule RNA, etc.

Small molecule RNA (20~300nt) includes miRNA, siRNA, piRNA, scRNA, snRNA, snoRNA, etc. Bacteria also have small molecule RNA (50~500nt).

Messenger RNA (mRNA), first discovered in 1960, is responsible for transmitting genetic information and directly directing protein synthesis during protein synthesis and has the following characteristics.

Transfer RNA (tRNA) is responsible for transporting amino acids and decoding the mRNA genetic code during protein synthesis. tRNA accounts for 10%-15% of total cellular RNA, and most of it is located in the cytoplasm. tRNA was proposed by Crick in 1955 and identified by Zamecnik and Hoagland in 1957.

Ribosomal RNA (rRNA) and ribosomal proteins form a nucleoprotein particle called a ribosome. There are about 15,000 ribosomes in a single E. coli.

The ribosomes of both prokaryotes and eukaryotes consist of a large subunit and a small subunit, both of which are composed of rRNA and ribosomal proteins. The sizes of ribosomes, ribosomal subunits, and rRNA are generally expressed as sedimentation coefficients.

Prokaryotes have only one type of ribosome, while eukaryotes have the following types located in different parts of the cell: ribosomes, free ribosomes, endoplasmic reticulum ribosomes (also known as attached ribosomes), mitochondrial ribosomes, and chloroplast ribosomes (plants).

Free ribosomes and endoplasmic reticulum ribosomes are actually the same types of ribosomes, they are larger than prokaryotic ribosomes and contain more rRNA and protein. Mitochondrial ribosomes and chloroplast ribosomes are smaller than prokaryotic ribosomes. However, the basic structure and function of these ribosomes are the same.

Correct Answer

Here is the correct answer to You can tell that this is an image of a DNA nucleotide and not an RNA nucleotide because you see a _____.

You can tell that this is an image of a DNA nucleotide and not an RNA nucleotide because you see a sugar with two, and not three, oxygen atoms

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